Abundance Of Large Trees Research Articles

Structural changes and carbon reduction due to habitat loss in Atlantic Forest

Habitat loss is a significant threat to biodiversity in tropical forests, leading to changes in composition, structure, and function. In this study, we aimed to evaluate the influence of the forest amount at the landscape scale on the structure and the stored carbon of tree communities. Eleven landscape samples of 36 km2 (6 × 6 km), with different amounts of forest cover at the landscape scale (between 5 and 60%), were randomly selected within a wide latitudinal range of Atlantic Forests in Brazil. We also used a sample design to control and avoid some biases in landscape-scale studies during the landscape selection, such as the rescue effect from the surrounding landscapes, differences in matrix permeability in each landscape, and the control for the same vegetation type or successional stage. In each selected landscape, we surveyed all woody individuals with a diameter at breast height (DBH) ≥ 2.5 cm in eight plots of 250 m2, randomly placed in the landscape’s forested areas. The structural variables evaluated were: total abundance, the abundance of prominent families, the abundance of large trees (DBH ≥ 30 cm), mean DBH, and average height, besides carbon storage. From the set of 8,179 individuals, we observed a positive correlation between forest amount and the total abundance, the abundance of large trees, and carbon stock. The abundance of the prominent hardwood tree families were positively correlated with forest amount. When comparing the two landscapes with the lowest proportion of habitats (5–15%) and the highest proportion (55−60%), almost one thousand trees and more than 150 T of carbon per hectare are lost. This reduction in the overall abundance and carbon indicates no compensatory effects on the tree community due to a turnover in composition or substitution of large trees for smaller ones. The Atlantic Forest is undergoing a process of homogenization and functional collapse, derived directly or indirectly from habitat loss, leading to a possible regime shift.

Anthropogenic and hurricane disturbances had similar negative effects on epiphytic Tillandsia species in a tropical dry forest

The distribution of epiphytes in tropical dry forests has been associated with the availability and traits of their phorophytes. Thus, strong disturbances of the phorophyte community are expected to affect the abundance and composition of epiphytes. Here, we address the effects of anthropogenic and hurricane disturbances on the richness and abundance of Tillandsia species in a tropical dry forest of Mexico. Tillandsia species were sampled at sites corresponding to early, intermediate, and late stages of succession in 2007 and 2016, before and after two successive large hurricanes, Jova (October 2011; Category 2) and Patricia (October 2015; Category 5). Tillandsia species richness and abundance were greater in the late successional stage compared with intermediate and early stages, which did not differ from each other. In addition, both richness and abundance were positively correlated with the abundance of large trees. Tillandsia species richness and abundance were greater before than after hurricanes. We conclude that only old-growth forests or secondary forests in late successional stages can support large populations of Tillandsia species, probably because their recovery time is dependent on the presence of large host trees that provide higher quality substrates. Our results also demonstrated that catastrophic hurricane disturbances are important density-independent factors that decrease the species richness and abundance of Tillandsia epiphytes in tropical dry forests.

Conserving Dry Old-Growth Forest in Central Oregon, USA

Logging and fire suppression have reduced the number of large old trees, increased the density of small shade-tolerant trees, and decreased forest resistance to fire, drought, insects, and disease in the interior Pacific Northwest. In Central Oregon, interim Old-growth definitions, the Deschutes Large Tree Layer, and the Gradient Nearest Neighbor (GNN) mapping tool are used to identify dry old-growth forests and guide forest planning. We used a recent characterization of dry old forests to evaluate interim old-growth definitions and GNN mapping. Historical old tree species composition should be used in old-growth definitions. The 21-in.-diameter harvest limitation maintains large trees but fails to protect smaller old individuals; it does not allow for removal of younger large shade-tolerant species more prevalent since fire suppression. GNN mapping accurately identified old forest based on abundance of large trees at a coarse landscape scale but was less accurate at a finer stand scale.

How does forest fragmentation affect tree communities? A critical case study in the biodiversity hotspot of New Caledonia

Context: The biodiversity hotspot for conservation of New Caledonia has facing high levels of forest fragmentation. Remnant forests are critical for biodiversity conservation and can help in understanding how does forest fragmentation affect tree communities. Objective: Determine the effect of habitat configuration and availability on tree communities. Methods: We mapped forest in a 60 km2 landscape and sampled 93 tree communities in 52 forest fragments following stratified random sampling. At each sampling point, we inventoried all trees with a diameter at breast height ≥10 cm within a radius of 10 m. We then analysed the response of the composition, the structure and the richness of tree communities to the fragment size and isolation, distance from the edge, as well as the topographical position. Results: Our results showed that the distance from the forest edge was the variable that explained the greatest observed variance in tree assemblages. We observed a decrease in the abundance and richness of animal-dispersed trees as well as a decrease in the abundance of large trees with increasing proximity to forest edges. Near forest edges we found a shift in species composition with a dominance of stress-tolerant pioneer species. Conclusions: Edge-effects are likely to be the main processes that affect remnant forest tree communities after about a century of forest fragmentation. It results in retrogressive successions at the edges leading to a dominance of stress-tolerant species. The vegetation surrounding fragments should be protected to promote the long process of forest extension and subsequently reduce edge-effects.

Effects of peat swamp logging and agricultural expansion on species richness of native mammals in Peninsular Malaysia

The biodiversity inhabiting tropical peat swamp forests in Southeast Asia is currently threatened by commercial logging and agricultural expansion. The occurrence of mammals in such forests is often poorly known and the factors influencing their occurrence in these ecosystems have rarely been quantified. We aim to determine the key habitat and landscape drivers of mammal species richness in fragmented peat swamp reserves. We conducted camera trap surveys in the North Selangor Peat Swamp Forest (NSPSF), the last remaining area of peat swamp forest on the west coast of Peninsular Malaysia. We also measured vegetation structure and landscape metrics to investigate the relationship between these factors and mammal richness. We recorded a total of 16 mammal species from 45 sampling sites using camera traps located in peat swamp forest reserves. Mammal species richness increased with the abundance of large trees and distance away from roads. Species richness decreased significantly with canopy cover and height, the abundance of fallen trees, the abundance of forest palms and saplings, distance away from rivers, and a measure of landscape compositional heterogeneity. Our findings underscore the high conservation value of logged peat swamp forests and the urgent need to halt further deforestation. We recommend: (1) protecting riparian habitat; (2) avoiding further forest conversion particularly areas supporting large trees into oil palm plantations; and (3) limiting road development within and around the NSPSF.

Historical and current forest conditions in the range of the Northern Spotted Owl in south central Oregon, USA

Restoration to increase resilience to current and projected drought and fire in historically open-canopy forests in fire-prone environments may be constrained by concern for species that favor dense forest conditions. To assist the recovery of a threatened species, the Northern Spotted Owl (NSO), in dry forest environments, the US Fish & Wildlife Service (USFWS) recommends embedding NSO conservation and recovery in restoration efforts that enable ecosystem recovery from past management actions and increase resilience to changing climate. In this study, we assessed changes between historical and current (1) forest structure and composition and (2) extent of NSO nesting and roosting (NR) or foraging (F) forest cover on 39,000ha at the eastern edge of the current designation of the range of the NSO. Historical records depict a predominantly open-canopy landscape dominated by large ponderosa pine. Current conditions include more than a 600% increase in trees 15–53cmdbh, substantial decline in trees ⩾81cmdbh, loss of the widespread distribution of trees ⩾53cmdbh, and loss of the dominance of ponderosa pine on mixed conifer sites. NSO habitat assessment involves a suite of attributes including: landscape context; species composition; canopy cover; basal area; average tree diameter; diameter diversity; and abundance of large trees, snags, canopy layers, coarse woody debris, and mistletoe. We tested for the presence of forest that met USFWS threshold values for two of these variables, canopy cover and basal area. Historically none of the area met the 60% canopy cover threshold for NR or F forest cover and almost none meets it currently. However, several NSO nesting pairs and individual birds have been observed in the study area over the last 20years, and studies in other frequent-fire forests show that canopy cover as low as 50% may be functional for NSO. To assess the implications of lower threshold values, we tested for NR or F forest cover presence at half the recommended thresholds, considerably below published estimates. Only five percent of the area exceeded 30% canopy cover historically; much of the current forest exceeds it today. Increase in canopy cover comes at the expense of increasing vulnerability to fire and drought and loss of historical functions and processes. Conflicting objectives of forest restoration and maintenance of spotted owl habitat on this site – isolated habitat in the dry margin of the range of the NSO – raises questions about how to achieve forest restoration in altered landscapes where existing, novel conditions favor at-risk species.

Deadwood stocks increase with selective logging and large tree frequency in Gabon.

Deadwood is a major component of aboveground biomass (AGB) in tropical forests and is important as habitat and for nutrient cycling and carbon storage. With deforestation and degradation taking place throughout the tropics, improved understanding of the magnitude and spatial variation in deadwood is vital for the development of regional and global carbon budgets. However, this potentially important carbon pool is poorly quantified in Afrotropical forests and the regional drivers of deadwood stocks are unknown. In the first large-scale study of deadwood in Central Africa, we quantified stocks in 47 forest sites across Gabon and evaluated the effects of disturbance (logging), forest structure variables (live AGB, wood density, abundance of large trees), and abiotic variables (temperature, precipitation, seasonality). Average deadwood stocks (measured as necromass, the biomass of deadwood) were 65Mg ha-1 or 23% of live AGB. Deadwood stocks varied spatially with disturbance and forest structure, but not abiotic variables. Deadwood stocks increased significantly with logging (+38Mg ha-1 ) and the abundance of large trees (+2.4Mg ha-1 for every tree >60cm dbh). Gabon holds 0.74Pg C, or 21% of total aboveground carbon in deadwood, a threefold increase over previous estimates. Importantly, deadwood densities in Gabon are comparable to those in the Neotropics and respond similarly to logging, but represent a lower proportion of live AGB (median of 18% in Gabon compared to 26% in the Neotropics). In forest carbon accounting, necromass is often assumed to be a constant proportion (9%) of biomass, but in humid tropical forests this ratio varies from 2% in undisturbed forest to 300% in logged forest. Because logging significantly increases the deadwood carbon pool, estimates of tropical forest carbon should at a minimum use different ratios for logged (mean of 30%) and unlogged forests (mean of 18%).

Local and regional determinants of vascular epiphyte mortality in the Andean mountains of Colombia

Summary We present the first large‐scale assessment of vascular epiphyte mortality in the neotropics. Our goals were to explore the primary types of vascular epiphyte death and to identify local and regional determinants of epiphyte mortality in natural forests located 60 to 2900 m a.s.l. in the Colombian Andes. Based on two consecutive annual surveys, we followed the fate of 4247 epiphytes to estimate the epiphyte mortality rate on 116 host trees at nine sites. A logistic regression analysis for proportional data with a binomial distribution of the error was applied to determine the probability of epiphyte death in relation to local and regional explanatory variables. The overall epiphyte mortality rate was 7.5 ± 1.1% year−1 (mean ± standard error). Non‐mechanical factors, such as desiccation, accounted for a mortality rate of 1.9 ± 0.3% year−1. Mechanical factors, such as falling branches, accounted for a mortality rate of 5.6 ± 1.1% year−1. According to generalized linear modelling analyses, both local and regional factors played key roles in determining epiphyte mortality. The actual evapotranspiration (regional factor) and the mean epiphyte attachment height (local factor) were both consistently positively associated with the probability of epiphyte death. Additional variables identified as possible determinants of the epiphyte mortality were the temperature seasonality, annual temperature range, the height and number of branches of the tree and the abundance of large trees (DBH ≥10 cm). Synthesis. The recorded high mortality rate indicates that natural epiphyte assemblages must be highly dynamic to avoid local extinction of species. Our study identifies actual evapotranspiration as an important driver of epiphyte mortality, and we highlight its importance in determining the fate tropical epiphyte communities may experience if evapotranspiration increases due to climate change. We hope our study addresses the paucity of research on non‐tree growth forms, typically ignored in vegetation dynamics, and encourages their inclusion in future studies that investigate the function of tropical ecosystems.

The history and natural regeneration of a secondary oak-beech woodland on a former wood-pasture in Hungary

Characteristic features of European woodland include both a reduction in natural forest areas and an increase in former agricultural areas occupied by secondary woodland. The management of these areas is challenging in terms of nature conservation, agricultural and forestry management and policy. The aim of our study was to reconstruct the history and to document the current tree stand structure for a secondary oak-beech woodland in Hungary. Towards the end of the 1800s, this area which was once almost completely occupied by a continuous forest, had been transformed into a wood-pasture. As a result of its gradual abandonment, the closed forest stand of the pasture increased from 10 to 52% between 1963 and 2005. The most characteristic feature of this woodland is the abundance of large trees. Globally, the number of large and ancient trees is rapidly diminishing. Therefore preserving and maintaining such areas, where large trees could live, is an essential management task.

Tropical forest wood production: a cross‐continental comparison

Summary Tropical forest above‐ground wood production (AGWP) varies substantially along environmental gradients. Some evidence suggests that AGWP may vary between regions and specifically that Asian forests have particularly high AGWP. However, comparisons across biogeographic regions using standardized methods are lacking, limiting our assessment of pan‐tropical variation in AGWP and potential causes. We sampled AGWP in NW Amazon (17 long‐term forest plots) and N Borneo (11 plots), both with abundant year‐round precipitation. Within each region, forests growing on a broad range of edaphic conditions were sampled using standardized soil and forest measurement techniques. Plot‐level AGWP was 49% greater in Borneo than in Amazonia (9.73 ± 0.56 vs. 6.53 ± 0.34 Mg dry mass ha−1 a−1, respectively; regional mean ± 1 SE). AGWP was positively associated with soil fertility (PCA axes, sum of bases and total P). After controlling for the edaphic environment, AGWP remained significantly higher in Bornean plots. Differences in AGWP were largely attributable to differing height–diameter allometry in the two regions and the abundance of large trees in Borneo. This may be explained, in part, by the greater solar radiation in Borneo compared with NW Amazonia. Trees belonging to the dominant SE Asian family, Dipterocarpaceae, gained woody biomass faster than otherwise equivalent, neighbouring non‐dipterocarps, implying that the exceptional production of Bornean forests may be driven by floristic elements. This dominant SE Asian family may partition biomass differently or be more efficient at harvesting resources and in converting them to woody biomass. Synthesis. N Bornean forests have much greater AGWP rates than those in NW Amazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why Asian forests produce wood half as fast again as comparable forests in the Amazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history.

Historical structure and composition of ponderosa pine and mixed-conifer forests in south-central Oregon

We summarized structure and composition of dry forests from a 90-year-old timber inventory collected by the Bureau of Indian Affairs on the former Klamath Indian Reservation (now part of the Fremont-Winema National Forest). This analysis includes data from 424,626 conifers ⩾15cmdbh on 3068 transects covering 6646ha. The data represent a 10–20% sample of 38,651ha of forest growing on sites that are classified as ponderosa pine (Pinus ponderosa) and mixed-conifer habitat types distributed within the 117,672 ha of the study area. Large, drought- and fire-tolerant ponderosa pine dominated these forests. Large tree (>53cmdbh) basal area (13±7m2/ha) contributed 83±16% of total basal area; 81±20% of the large-tree basal area was ponderosa pine. Composition and structure of forests on mixed-conifer sites were very similar to those on ponderosa pine sites. Variability in composition and structure was recorded on all habitat types and was highest on moist mixed-conifer sites. Stand densities (trees per hectare, tph) have more than tripled over the past 90years from 68±28tph to a current density of 234±122tph recorded in Current Vegetation Survey data collected by the United States Forest Service. Mean basal area, however, increased by less than 20%. Basal area of large trees (>53cmdbh) has declined by >50%, and the abundance of large trees as a proportion of the total number of trees per hectare has decreased by more than a factor of five. This landscape-level record of historical forest conditions allows inferences about structure and composition across tens of thousands of hectares. A historical landscape emerges which supports current working hypotheses that frequent, low- to moderate-severity wildfires maintained a predominantly low-density forest dominated by large, fire- and drought-tolerant ponderosa pines across a significant moisture and productivity gradient from the driest ponderosa pine to the mixed-conifer habitat types.

Effect of anthropogenic disturbance on the abundance and habitat occupancy of two endemic hornbill species in Buton island, Sulawesi

SummaryThe Red-knobbed HornbillRhyticeros cassidixand the Sulawesi Tarictic HornbillPenelopides exarhatusare endemic to Sulawesi. This study assessed the effect of anthropogenic disturbance on these two species in Lambusango forest, Buton, south-east Sulawesi. Data were collected between 2005 and 2007 in six study sites which varied in their levels of disturbance. Two of the lightly disturbed and two of the more heavily disturbed sites were within ‘protection forest’ whereas the rest were classified as ‘production forest’. We used point counts with distance sampling to survey the hornbills. Habitat data were also collected at each of the points and related to hornbill ‘occupancy’ with the program PRESENCE. Both hornbills were estimated to be at higher density in the lightly disturbed forest but the level of disturbance had more of a detrimental effect on Red-knobbed Hornbill than on Sulawesi Tarictic Hornbill. Lightly disturbed forest had significantly more large trees than the heavily disturbed forest but there was no difference in the abundance of figs. Using four covariates (disturbance level, protection status, number of large trees, and number of figs), 99% of presence/absence of Red-knobbed Hornbills at the points could be explained by habitat disturbance and 87% by forest status; the same covariates explained 76% of presence/absence for the Sulawesi Tarictic Hornbill with abundance of large trees as the most important factor. These results support the notion that Red-knobbed Hornbill is more sensitive to anthropogenic disturbance and its conservation is highly dependent upon the preservation of forest habitats with low levels of disturbance.

Profound impoverishment of the large-tree stand in a hyper-fragmented landscape of the Atlantic forest

Large tree species have a disproportional influence on the structure and functioning of tropical forests, but the forces affecting their long-term persistence in human-dominated landscapes remain poorly understood. Here we test the hypothesis that aging forest edges and small fragments (3.4–295.7 ha) are greatly impoverished in terms of species richness and abundance of large trees in comparison to core areas of forest interior. The study was conducted in a hyper-fragmented landscape of the Atlantic forest, northeast Brazil. Large tree species were quantified by recording all trees (DBH ≥ 10 cm) within fifty-eight 0.1-ha plots distributed in three forest habitats: small forest fragments ( n = 28), forest edges ( n = 10), and primary forest interior areas within an exceptional large forest remnant ( n = 20). Large tree species and their stems ≥10 cm DBH were reduced by half in forest edges and fragments. Moreover, these edge-affected habitats almost lacked large-stemmed trees altogether (0.24 ± 0.27% of all stems sampled), and very tall trees were completely absent from forest edges. In contrast, large trees contributed to over 1.5% of the whole stand in forest interior plots (2.9 ± 2.8%). Habitats also differed in terms of tree architecture: relative to their DBH trees were on average 30% shorter in small fragments and forest edges. Finally, an indicator species analysis yielded an ecological group of 12 large tree species that were significantly associated with forest interior plots, but were completely missing from edge-affected habitats. Our results suggest a persistent and substantial impoverishment of the large-tree stand, including the structural collapse of forest emergent layer, in aging, hyper-fragmented landscapes.

Modelling ungulate dependence on higher quality forage under large trees in African savannahs

In African savannahs, large trees improve grass quality, particularly in dry and nutrient poor areas. Enhanced below-canopy grass nutrients, such as nitrogen and phosphorus contents should therefore attract and benefit grazers. To predict whether ungulates really need these forage quality islands we focused on four grazer species, i.e., zebra, buffalo, wildebeest, and warthog, differing in body size and digestive system. We confronted literature estimations of their feeding requirements with forage availability and quality, observed in three South African savannah systems, through linear modelling. The model predicted the proportion of below-canopy grass that grazers should include in their diet to meet their nutritional requirements. During the wet season, the model predicted that all animals could satisfy their daily nutrient requirements when feeding on a combination of below- and outside-canopy grasses. However, wildebeest, having relatively high nutrient demands, could meet their nutrient requirements only by feeding almost exclusively below canopies. During the dry season, all animals could gain almost twice as much digestible protein when feeding on below – compared to outside-canopy forage. Nonetheless, only warthogs could satisfy their nutrient requirements – when feeding almost exclusively on below-canopy grasses. The other ungulate species could not meet their phosphorus demands by feeding at either site without exceeding their maximum fibre intake, indicating the unfavourable conditions during the dry season. We conclude that grazing ungulates, particularly warthog, zebra, and buffalo, actually depend on the available below-canopy grass resources. Our model therefore helps to quantify the importance of higher quality forage patches beneath savannah trees. The composition of grazer communities depending on below-canopy grasses can be anticipated if grazer food requirements and the abundance of large trees in savannahs are known. The model suggests that the conservation of large single-standing trees in savannahs is crucial for maintenance of locally grazing herbivores. Grosse Bäume in afrikanischen Savannen können, vor allem in trockenen und nährstoffarmen Gebieten, die Grasqualität signifikant verbessern. Eine erhöhte Grasqualität unterhalb des Baumkronenbereichs, wie sie in drei südafrikanischen Savannenlandschaften gemessen wurde, kann demzufolge grasfressende Tierarten anziehen und für diese von großem Nutzen sein. Wir untersuchten als Beispiel vier grasfressende Paarhuferarten, Zebra, Büffel, Gnu und Warzenschwein, die sich durch ihre Körpergröße und ihr Verdauungssystem unterscheiden. Mit Hilfe eines linearen Programm-Modells konnten wir voraus sagen, ob diese grasfressenden Tierarten ihren Nährstoffbedarf während verschiedener Jahreszeiten erfüllen können, wenn sie unterhalb der Baumkronen fressen. Während der Regenzeit konnten alle Tierarten ihren täglichen Nährstoffbedarf decken und profitierten vom nährstoffreichen Gras, das unter Bäumen wuchs. Gnus schienen Schwierigkeiten zu haben, ihren hohen Qualitätsansprüchen zu genügen, aber sie konnten ihren Nährstoffeintrag effektiv erhöhen, wenn sie sich fast gänzlich vom Gras unter Bäumen ernährten. In der Trockenperiode konnten alle Tierarten beinahe zweimal so viel verdaubares Protein zu sich nehmen, wenn sie statt ausserhalb der Baumkronen unter Bäumen frassen. Allerdings waren die Warzenschweine als einzige Spezies in der Lage, ihren Nährstoffbedarf gänzlich zu decken, und dies nur, wenn sie zu 100% unter Bäumen frassen. Demgegenüber konnten die anderen Tierarten ihren Phosphorbedarf nicht decken, ohne den maximal durch ihr Verdauungssystem abbaubaren Fasergehalt zu überschreiten. Wir schließen daraus, dass grasfressende Tierarten, insbesondere Warzenschwein, Zebra und Büffel, effektiver fressen können, wenn sie die vorhandenen Grasressourcen unterhalb der Baumkronen nutzen. Unser Modell kann dazu beitragen, Futterpräferenzen und Grasfresser-Bewegungen vorauszusagen, wenn Futter-Ressourcen räumlich uneinheitlich verteilt sind. In Savannen kann somit die Zusammensetzung der Gemeinschaft der Grasfresser, die in von der Grasqualität unterhalb der Bäume abhängt, vorausgesagt werden, wenn deren Nährstoffbedarf einerseits und der Baumbewuchs andererseits bekannt ist. Unsere Ergebnisse heben die Wichtigkeit der Bäume für den Erhalt von Grasfressern hervor, und wir empfehlen, große Savannenbäume und damit auch die grasfressenden Tierarten zu schützen.

Salvage Logging in the Montane Ash Eucalypt Forests of the Central Highlands of Victoria and Its Potential Impacts on Biodiversity

The two major forms of disturbance in the montane ash eucalypt forests of the Central Highlands of Victoria (southeastern Australia) are clearfell logging and unplanned wildfires. Since the 1930s wildfire has been followed by intensive and extensive salvage-logging operations, which may proceed for many years after a wildfire has occurred. Although applied widely, the potential effects of salvage logging on native flora and fauna have been poorly studied. Our data indicate that the abundance of large trees with hollows is significantly reduced in forests subject to salvage harvesting. This has implications for thepersistence of an array of such cavity-using vertebrates as the endangered arboreal marsupial, Leadbeater's possum (Gymnobelidues leadbeateri). Salvage logging also reduces the prevalence of multiaged montane ash forests--places that typically support the highest diversity of arboreal marsupials and forest birds. Limited research has been conducted on the effects of salvage logging on plants; thus, we constructed hypotheses about potential impacts for further testing based on known responses to clearfell logging and key life history attributes. We predict many species, such as vegetatively resprouting tree ferns, will decline, as they do after clearfelling. We also suggest that seed regenerators, which typically regenerate well after fire or conventional clearfelling, will decline after salvage logging because the stimulation for germination (fire) takes place prior to mechanical disturbance (logging). Understoryplant communities in salvage-logged areas will be dominated by a smaller suite of species, and those that are wind dispersed, have viable soil-stored seed remaining after salvage logging, or have deep rhizomes are likely to be advantaged. We recommend the following improvements to salvage-logging policies that may better incorporate conservation needs in Victorian montane ash forests: (1) exemption of salvage logging from some areas (e.g., old-growth stands and places subject to only partial stand damage); (2) increased retention of biological legacies on burned areas through variations in the intensity of salvage logging; and (3) reduction in the levels of physical disturbance on salvage-logged areas, especially through limited seedbed preparation and mechanical disturbance.

Impacts of timber harvesting on mammals, reptiles and nocturnal birds in native hardwood forests of East Gippsland, Victoria: a retrospective approach

Summary The occurrence of mammals, reptiles and nocturnal birds was assessed in a series of successional forest sites in East Gippsland, Victoria, Australia. A total of 63 sites, representing three major forest types (Wet, Damp and Lowland) and six different forest age classes (2, 5, 10, 18, 25 y after logging and unharvested), was sampled using a range of census techniques, with each combination of forest type and age class replicated. Totals of five nocturnal bird, twenty mammal and seven reptile species were recorded during this study. Key species were selected for subsequent analysis, representing three major faunal assemblages (arboreal mammals and nocturnal birds, ground-dwelling mammals, and heliothermic reptiles). Generalised linear modelling was used to investigate the relationship between the occurrence and diversity of species within each faunal assemblage with respect to the design variables (forest type and age class). To help explain any observed intra-age-class variation in animal occurrence or diversity, structural attributes were also analysed. The study highlights the importance of retained habitat attributes (old-growth legacies) within logged forest if wildlife conservation is to be a priority. The presence and abundance of large trees were the most important habitat variables for hollow-dependent fauna such as the southern boobook and yellow-bellied glider. The southern boobook and native rodents (Rattus spp.) were most likely to be found in unharvested forest, implying a negative impact of timber harvesting. The black wallaby was the only species to show a preference for younger age classes, an expected response from a species known to browse on regrowth seedlings. The mountain brushtail possum was more likely to be found on smaller coupes. Lowland forest supported the greatest species diversity of ground-dwelling mammals when only the design variables were considered. When effects of tree height and aspect were considered separately in the model, the trend was for greater species diversity in Damp forest. It is recommended that any increase in logging intensity in either Damp or Lowland forest should be balanced with suitable measures to protect sites of high conservation value. In the short term, no single species of heliothermic reptile appeared to be disadvantaged by logging operations. Spencer's skink may benefit from an increase in regrowth forest, provided large retained trees can be used as basking sites above the regrowth canopy. Species diversity of reptiles was affected adversely by harvesting in the Lowland forests and positively in the Wet forests. The protection of microhabitat attributes during timber harvesting operations may be one management strategy that would favour the long-term survival of forest reptiles in a logged area.

Roosting, range use and foraging behaviour of the Sickle-billed Vanga, Falculea palliata, in Madagascar

Roosting behaviour, range use and foraging behaviour of non-breeding Sickle-billed Vangas, Falculea polliata, a Malagasy endemic, were studied in the Ankarafantsika Strict Nature Reserve, northwestern Madagascar, in 1996 and 1997. Non-breeding birds farmed a flock and ranged daily between communal roosts and foraging areas. Roost sites were tall eucalypt trees (20–30 m) situated outside the forests, and the same trees were used repeatedly. Roosting flock size decreased during the breeding season, from October to December, due to the departure of breeding individuals. Mean sizes of daily home range and of foraging area were 68.6 ha (45–100 ha) and 14.1 ha (6–25 ha), respectively; much larger than those of breeding birds (3 ha). Sickle-billed Vangas foraged by probing their long and slender curved bills into holes and cracks in tree trunks or large branches. Dead trees or dead sections of live trees were preferred. The high abundance of large trees or dead trees in the deciduous forests allowed the flock to forage exclusively in this habitat. We suggest that communal roosts are located outside forests to avoid disturbance or predation by mammals. A foraging flock of Sickle-billed Vangas makes a round trip daily between the safe roosting sites and good foraging areas.

Nest-Site Selection by Female Black-Capped Chickadees: Settlement Based on Conspecific Attraction?

Female Black-capped Chickadees (Poecile atricapillus) solicit extrapair copu- lations (EPCs) from neighboring high-ranked males, and these EPCs result in extrapair young. Females might choose to locate their nests near the territory boundaries of attractive males to facilitate access to EPCs. Other hypotheses might also explain choice of nest site, namely: (1) habitat characteristics, (2) prey abundance, and (3) previous experience. We test- ed these four hypotheses in 1996 and 1997. Out of 27 habitat characteristics measured, we found only one that was significantly different between nests and control sites in both years. The abundance of large trees was lower at nest sites than at control sites in each year and when years were pooled. Relative prey abundance did not differ between nests and control sites for either year of the study. We found no difference in interyear nest placement based on female experience; experienced females nested farther than 60 m from their previous nest sites in both years of the study. In 1996, females whose neighboring males were higher ranked than their social partner located their nests significantly closer to territory bound- aries than did females whose nearest neighbors were lower ranked than their social partner. In 1997, all pairs nested near territory boundaries. We conclude that choice of nest location in Black-capped Chickadees is influenced by conspecific attraction based on mating tactics.

A method for predicting the spatial distribution of arboreal marsupials

A method is described for predicting the spatial distribution of arboreal marsupials. The approach is demonstrated using a statistical habitat association model for the greater glider (Petauroides volans), developed in the mountain ash (Eucalyptus regnans) forests of the central highlands of Victoria. The method is applied to predict the spatial distribution of P. volans in the Ada Forest Block, using forestinventory data on the values of the two significant variables in the statistical model (the age of a stand of forest and the abundance of large trees with hollows in a 3-ha area). The application of the model enabled values for the estimated probability of occurrence of P, volans (with a 95% confidence interval) to be generated for each of approximately 2200 3-ha pixels in the Ada Forest Block. A kernel smoothing procedure was then applied to allow for the spatial dependence implicit in these data. The standard measures of statistical uncertainty employed in our analysis revealed substantial variation in the predicted probability of occurrence of P. volans, even though the terms in the statistical relationship were highly significant. However, whilst the model is unable to reliably predict the occurrence of P. volans at any given 3-ha site, tests of the performance of the model showed that it performed well when the results of field surveys were aggregated over many sites. The results of our analysis emphasise the importance of including measures of uncertainty in spatial predictions generated from statistical models.